I couldn’t get it to work either. I ended up using a text field with a wrapper class (attribute) on the field, and used https://github.com/xdan/datetimepicker with a target of that field element. Working well so far.

Nevermind I figured it out. Here is the code if it helps someone:

In my setup plugin:

// DATETIMEPICKER ENQUEUE

add_filter('piklist_assets', 'my_assets');

function my_assets($assets)
{
  array_push($assets['scripts'], array(
    'handle' => 'datetimepicker'
    ,'src' => get_template_directory_uri() . '/js/jquery.datetimepicker.full.js'
    ,'ver' => '2.5.4'
    ,'deps' => 'jquery'
    ,'enqueue' => true
    ,'in_footer' => true
    ,'admin' => true
    ,'front' => false
  ));

 array_push($assets['scripts'], array(
    'handle' => 'dtpickermine'
    ,'src' => get_template_directory_uri() . '/js/dtpickermine.js' //my jQuery(document).ready code...
    ,'ver' => '1.0'
    ,'deps' => 'jquery'
    ,'enqueue' => true
    ,'in_footer' => true
    ,'admin' => true
    ,'front' => false
  ));

  array_push($assets['styles'], array(
    'handle' => 'datetimepickerclasses'
    ,'src' => get_template_directory_uri() . '/js/jquery.datetimepicker.css'
    ,'ver' => '1.2'
    ,'enqueue' => true
    ,'in_footer' => true
    ,'admin' => true
    ,'media' => 'screen, projection'
  ));
  
  return $assets;
}  

And then in my meta field definition:

piklist('field', array(
 'type' => 'text'
   ,'field' => 'ae_dtpicker'
   ,'label' => __('my date time', 'direct-action')
    ,'attributes' => array(
      'class' => 'dtpicker'
    )
  ));